infinitive = гото́вить. Готовить has two meanings: 1) to make food 2) to prepare or make something/somebody prepared/ready.
Я готовлю пирог = I cook pie.
Я готовлю студента к экзамену = I am preparing the student for the exam.
Я готовлюсь к экзамену = I am preparing for the exam.
By the way, notice the "-сь", it and "-ся" at the verb's end usually means "myself/itself/themselves". Like "I make myself ready to exam"
But there are some exceptions like "целоваться" (to kiss), here we see "-ся", but nobody kisses themselves, "ты целуешься с ним" means that you are in process of kissing with him, not with yourself! :D
P.S. "Мы готовим суши" sounds pretty strange, cause "готовить" in cooking-context means food+high temperature (to fry, to boil, to stew, etc), and sushi usually is made of raw products. If I was making sushi, I'd say "Я делаю суши" (I make/am making sushi).
The land is сУша, not сУши (at least in nominative case). And it is uncountable, so it should sound like "мы готовим сУшу", not "суши".
The word суша came from сухой, what means "dry". So we use it mostly in cpntrast ofocean, water, etc. For example, in sentences like "2/3 of the Earth is covered by water and only 1/3 by land". When farmer wants to say "we are preparing the land", he will say "мы подготАвливаем зЕмли" or something like this (the word земля has more than one meaning: with the capital letter it means the Earth, without it means both land and ground [or how do you call the substance in planters? We call it землЯ, пОчва и грунт, but the first one is more useful and less specific than others])